If you are using Ubuntu Dapper Drake, you could press CTRL+SHIFT and then the unicode for special characters so you didn't have to copy and paste them from the Character palette every time you wanted to use them.

Solution1

If you are using Edgy this will not work any more here is simple tip how to use Special Characters.You need to use compose key

If you want to enable compose key go to System ---> Preferences ---> Keyboard

If you can't make fractions like ½ with the above solution you can fix that using the following procedure

you need to edit the /etc/environment file using the following command

sudo vi /etc/environment

add the following line

export GTK_IM_MODULE=xim

Save the file and exit

Now you need to copy this file to your home directory

cp /usr/share/X11/locale/en_US.UTF-8/Compose ~/.XCompose

This will give you a more complete character set.For example that your keyboard doesn't have a tilde (~). You can change the lines that require entering a tilde so that a simple "t" (or whatever you like) will work. Just don't use a key combination that's already in use.